Relation between tumor treating fields usage rate ≥75% for the first 3 months and progression-free survival in patients with newly diagnosed WHO grade 4 gliomas

Background Tumor treating fields (TTFields) therapy is an important treatment for glioblastoma. However, there have been few reports showing the effectiveness thereof in clinical settings worldwide. The aim of this study was to examine the efficacy of TTFields therapy by comparing patients with compliance rates above 75% with those below 75% during the first 3 months of treatment. Methods Data were retrospectively collected from electronic medical records for consecutive patients with newly diagnosed World Health Organization grade 4 gliomas who received TTFields therapy at 12 institutes in Japan from January 2018 to December 2023. Results In total, 157 patients received TTFields therapy. We analyzed 116 patients who used TTFields for at least the first 3 months. The median age was 57 years; 67 patients were male; and the median KPS before the start of adjuvant temozolomide was 90. The average compliance rate was 78.3%. The median progression-free survival (PFS) and overall survival (OS) were 11.9 months and 23.7 months, respectively. A high compliance rate of TTFields ≥75% for the first 3 months was achieved in 67 patients and was a significant prognostic factor on PFS (P=.04). The median PFS for patients with high and low compliance rates was 12.6 and 9.0 months, respectively; the median OS was 25.3 and 21.3 months, respectively (P=.15). Conclusions TTFields use rate ≥75% in the first 3 months was significantly associated with improved PFS. There was a tendency for OS to be extended. Further analysis with a larger number of cases is required.